Condensation products of hydroxycarboxylic acids and glycols or glycerol

ABSTRACT

The invention relates to reaction products of glycols, diglycols, higher glycols or glycerol with α-hydroxycarboxylic acids in a molar ratio of 1:2 or higher, especially conforming to the general formula (V) where R is hydrogen or a C 1-3  alkyl group, preferably methyl, nx is from 1 to 5, preferably from 1 to 3, n is 1 or 2 and when n=1 the radical R″ is C 1-4  alkylene, preferably ethylene, x is defined as x′ and y is not less than 1, preferably from 1 to 5, especially 1 or 2, and when n=2 the radical R″ is a glycerol radical, x is defined as x″ and y is 1.  
                 
 
     The invention further relates to the use of the (poly)hydroxycarboxylic acid (poly)glycol esters or (poly)hydroxycarboxylic acid glyceryl esters as acid donors and for controlling the pH in textile treatment processes.

[0001] The invention relates to reaction products of glycols, diglycolsor higher glycols and also glycerol with α-hydroxycarboxylic acids, andto the use thereof as acid donors and for controlling the pH in textiletreatment processes.

[0002] Textile treatment processes generally achieve uniform treatmentof the textile fibres by employing pH and/or temperature gradientsinstead of constant conditions. Especially the employment of a pHgradient demands an increased process engineering input, since forexample acid has to be continuously metered in to lower the pH.Processes are therefore in existence in the prior art where, to avoidthe metered addition of acid for example an agent is added that releasesthe requisite amount of acid incrementally with or without temperatureincrease.

[0003] CH patent 669882 utilizes reaction products of ethylene oxidewith formic acid and of ethylene glycol with formic acid and isopropylformate as acid donors. U.S. Pat. No. 4,568,351 describes reactionproducts of formic acid or β-hydroxycarboxylic acids with ethylene oxidefor use as acid donors.

[0004] The added compounds hydrolyse during the textile finishingoperation and make it possible to lower the pH of a liquor in steps. Indyeing processes for example the use of the aforementioned agentspermits a slow and uniformly progressive fixation, whereby a moreuniform dyeing is achieved.

[0005] JP patent 3083403 describes condensation products ofhydroxyl-substituted dicarboxylic acids with alkylene glycols which areuseful as levelling agents in dyeing processes for polyamide fibres.U.S. Pat. No. 3,600,121 describes esters of alkylcarboxylic acids andpolyethylene glycol as retarding agents for the uniform coloration ofcellulose fibres.

[0006] An important variable for determining the efficacy of theproducts used as acid donors and buffer compounds is the hydrolysisnumber. The hydrolysis number is determined as a characteristicparameter in the analysis of fats. The hydrolysis number is defined asthe amount of potassium hydroxide in milligrams (mg) needed toneutralize the esterified and unesterified fatty acids contained in 1 gof fat. The hydrolysis number is thus a measure of the amount of acidwhich can be released from an ester by complete hydrolysis. Thehydrolysis number should consequently also be determining for thetrajectory of the pH curve during a textile finishing operation.

[0007] It has now been surprisingly found that the reaction of anα-hydroxycarboxylic acid conforming to the general formula (I) with aglycol, diglycol or higher glycols conforming to the general formula(II) or with glycerol in a molar ratio of 2:1 or higher leads to anunexpected trajectory of the pH curve. Of particular advantage here arecondensation products of a diglycol or higher glycol with anα-hydroxycarboxylic acid in a molar ratio of 1:2 or higher, preferably1:2, 1:3 or 1:4. Since such condensation products are generallystatistical mixtures, the molar ratio need not necessarily be anintegral ratio.

[0008] Useful α-hydroxycarboxylic acids conform to the general formula(I)

[0009] where R is hydrogen or a C₁₋₃ alkyl group, preferably methyl.Condensation thereof with suitable glycols, diglycols or higher glycolsof the general formula (II)

[0010] where R′ is C₁₋₄ alkylene, preferably ethylene, and y is not lessthan 1, preferably from 1 to 5, especially 1 or 2, provides(poly)hydroxycarboxylic acid (poly)glycol esters of the general formula(III)

[0011] where R, R′ and y are each as defined above and x′ is from 1 to5. In preferred compounds, R is a methyl group, R′ is ethylene, x′ isfrom 1 to 3 and y is from 1 to 3. Particular preference is given tocompounds where x′ is from 1.5 to 2 and y is 1 or 2.

[0012] Condensation of suitable α-hydroxycarboxylic acids of the generalformula (I) with glycerol

[0013] provides (poly)hydroxycarboxylic acid glyceryl esters of thegeneral formula (IV)

[0014] where R is as defined above, the radical R″ is a glycerolradical, x″ is from 0.5 to 2.5, preferably from 0.5 to 1, and y is 1.What is decisive is the ratio of y to x″, so that in principle it isalso possible for just two hydroxyl groups of the glycerol or for allthree hydroxyl groups to be esterified with different numbers ofα-hydroxycarboxylic acids. x″ is to be understood as the average valueof the number of condensed α-hydroxycarboxylic acids. For a molar ratioof 1:2 for glycerol to α-hydroxycarboxylic acid, x″ is therefore 0.5.

[0015] The compounds are prepared by known methods. For instance,compounds of the formula (III) are obtainable by reaction of x′+1 mol ofan α-hydroxycarboxylic acid conforming to the formula (I) with 1 mol ofthe corresponding glycol, diglycol or higher glycol of the formula (II).The reaction products can if necessary be purified after isolation.

[0016] Compounds of the formula (IV) are obtainable by reaction of 2x″+1mol of an α-hydroxycarboxylic acid conforming to the formula (I) with 1mol of glycerol.

[0017] Owing to their higher degree of branching, the glycerolcondensation products obtained have a higher viscosity than thecorresponding glycol condensation products.

[0018] The invention thus provides compounds of the formula (V)

[0019] where R is hydrogen or a C₁₋₃ alkyl group, preferably methyl, nxis from 1 to 5, preferably from 1 to 3, n is 1 or 2 and

[0020] when n=1 the radical R″ is C₁₋₄ alkylene, preferably ethylene, xis defined as x′ and y is not less than 1, preferably from 1 to 5,especially 1 or 2 and

[0021] when n=2 the radical R″ is a glycerol radical, x is defined as x″and y is =1.

[0022] The hydrolysis number, which should be useful as an aciditymeasure of esters, is unexpectedly not correlated with the molareffectiveness as an acid donor in the case of the condensation productsaccording to the invention. On the contrary, it was surprisingly foundthat condensation products having a molar ratio of 1:2 or higher aremore effective than prior art condensation products having a molar ratioof 1:1 in terms of the molar amount used. The compounds according to theinvention are consequently of immense benefit, economically.

[0023] The compounds according to the invention may be useful as aciddonors in textile finishing processes without significantly increasingthe process engineering investment. The compounds according to theinvention hydrolyse in the course of the textile finishing process andpermit processing with variable pH at constant or variable temperatures.Generally, the abovementioned compounds are used to incrementally lowerthe pH of a liquor. But they can also be used for stabilizing the pH inacidic liquors in which the pH would otherwise rise in the course of thetreatment operation.

[0024] More particularly, the compounds according to the invention arealso useful for minimizing the changes in the pH of the liquor. This isparticularly advantageous when the textile treatment agent or dye isinstable to such changes.

[0025] The use as an acid donor and an agent for controlling the pH intextile treatment operations is particularly advantageous in dyeingprocesses for textiles made of natural, synthetic and semisyntheticfibres. Especially treatment operations under weakly alkaline or acidicconditions with constant or variable pH are of importance.

[0026] Useful natural textile materials include polyamides such as forexample wool or blends of natural fibres and synthetic polyamides, forexample nylon. Useful natural textile materials further includecellulose fibres, for example cotton, semisynthetic textile materials,for example cellulose acetates, and also mixtures thereof.

[0027] Useful wholly synthetic textile materials include linear aromaticpolyesters, for example polyethylene terephthalates, especially thecondensation products of terephthalic acid with glycols or with1,4-bis(hydroxymethyl)cyclohexane. Further polycarbonates, for examplefrom α,α-dimethyl-4,4′-dihydroxydiphenylmethane and phosgene, and alsopolyvinyl chlorides, polyacrylonitriles and polyamides.

[0028] The textile materials can be present in any conventional form,for example as fibres, yarns, webs, woven or non-woven textiles.

[0029] The compounds of the general formula (V) can be used either assuch or in the form of a preparation together with emulsifiers and/ordispersants.

[0030] Preference is given to using the compounds in concentrations of0.1 to 5 g/l, particularly preferably from 0.5 to 1 g/l.

[0031] Textile treatment processes for the purposes of the presentinvention are in the widest sense dyeing, printing and brighteningprocesses and also all finishing processes in which the pH has aninfluence on the effect of the process. The processes in question can becontinuous or batchwise.

[0032] Dyeing processes can utilize acid dyes, metal complex dyes,reactive dyes, basic dyes and disperse dyes together with the compoundsand processes according to the invention.

[0033] Preferred temperature ranges are from 20 to 140° C., especiallyfrom 70-100° C.

[0034] Preferred pH ranges are between 5 and 10 at the start of theprocess and between 3 and 7 at the end of the process. Depending on theamount of the compound used, the pH can be kept constant orincrementally reduced. The compounds according to the invention can beadded all at once or incrementally in the course of the process. Analkaline liquor can be adjusted with known agents, for example aqueoussodium hydroxide solution, sodium carbonate, borax, sodium acetate orammonia, at the start of the process.

EXAMPLES Preparation Example 1 (Comparative)

[0035] 462 g of lactic acid (78%), 248 g of ethylene glycol and 2 g ofsulphuric acid are heated to an internal temperature of 115° C. underreduced pressure and stirred at that temperature and under reducedpressure for 3 hours until distillate formation has virtually ceased.

[0036] This affords a polyester having a hydrolysis number of 406.

Preparation Example 2 (Comparative)

[0037] Example 1 is repeated to react 231 g of lactic acid (78%) with212 g of diethylene glycol to afford a polyester having a hydrolysisnumber of 286.

Preparation Example 3

[0038] Example 1 is repeated to react 462 g of lactic acid (78%) with124 g of ethylene glycol. The polyester obtained is 415 g of a yellowliquid having a viscosity of 1.4 Pas, a hydrolysis number of 529 and anM_(w) of 279.

Preparation Example 4

[0039] 600 g of lactic acid (78%), 81 g of ethylene glycol and 1 g ofsulphuric acid are heated to an internal temperature of 115° C. underreduced pressure and stirred at that temperature under reduced pressurefor 4 hours, during which 220 g of colourless distillate are separatedoff. This affords 460 g of a yellow viscous liquid (viscosity 25 Pas)having a hydrolysis number of 615 and an M_(w) of 472.

Preparation Example 5

[0040] Example 1 is repeated to react 231 g of lactic acid (78%) with106 g of diethylene glycol to afford a polyester having a hydrolysisnumber of 439 and an M_(w) of 276.

Preparation Example 6

[0041] 231 g of lactic acid (78%), 53 g of diethylene glycol and 0.5 gof sulphuric acid are heated to an internal temperature of 115° C. underreduced pressure and stirred at that temperature under reduced pressurefor 3 hours, during which 84 g of water are distilled off. This affords200 g of a yellow viscous liquid having a viscosity of 5 Pas, ahydrolysis number of 560 and an M_(w) of 441.

Preparation Example 7

[0042] Example 1 is repeated to react 565 g of glycolic acid (70%) with162 g of ethylene glycol to afford a polyester having a hydrolysisnumber of 600 and an M_(w) of 300.

Preparation Example 8

[0043] Example 1 is repeated to react 565 g of glycolic acid (70%) with81 g of ethylene glycol to afford a polyester having a hydrolysis numberof 707 and an M_(w) of 373.

Preparation Example 9

[0044] Example 1 is repeated to react 565 g of glycolic acid (70%) with276 g of diethylene glycol to afford a polyester having a hydrolysisnumber of 502 and an M_(w) of 257.

Preparation Example 10

[0045] Example 1 is repeated to react 565 g of glycolic acid (70%) with138 g of diethylene glycol to afford a polyester having a hydrolysisnumber of 636 and an M_(w) of 370.

Preparation Example 11 (Comparative)

[0046] Example 1 is repeated to react 231 g of lactic acid (78%) with184 g of glycerol to afford a polyester having a hydrolysis number of335, an M_(w) of 246 and a viscosity of 6 Pas.

Preparation Example 12

[0047] Example 1 is repeated to react 231 g of lactic acid (78%) with 92g of glycerol to afford a polyester having a hydrolysis number of 452,an M_(w) of 319 and a viscosity of 28 Pas.

Preparation Example 13

[0048] Example 1 is repeated to react 231 g of lactic acid (78%) with 61g of glycerol to afford a polyester having a hydrolysis number of 520,an M_(w) of 374 and a viscosity of 65 Pas.

Use Examples

[0049] The following experiments were carried out to test theeffectiveness of the individual condensation products as acid donors:

[0050] A certain amount of the compounds prepared according toPreparation Examples 1-8 was dissolved in 1 litre of demineralized watertogether with 50 mg of sodium carbonate, the resulting pH being about10. The amount of the experimental products was chosen so that theirconcentration in the solution corresponded to a hydrolysis number of425/1. This was followed by heating at a rate of 1°/min from 30° C. tothe boiling point over 70 minutes. During this period, the pH of thesolution was measured. The pH on attainment of the boiling point isreported in the following use experiments as a measure of theeffectiveness of the compounds.

Use Example A

[0051] Using 0.69 g of the product of Preparation Example 4, a final pHof 4.7 was reached. Using 0.80 g of the product of Preparation Example3, a final pH of 5.1 was reached. Using 1.05 g of a similarly preparedcondensation product of lactic acid and ethylene glycol in a molar ratioof 1:1 according to Preparation Example 1, the pH only decreased to 5.6.

Use Example B

[0052] Using 0.76 g of the product of Preparation Example 6, a final pHof 4.8 was reached. Using 0.97 g of the product of Preparation Example5, a final pH of 5.4 was reached. Using 1.49 g of a similarly preparedcondensation product of lactic acid and diethylene glycol in a molarratio of 1:1 according to Preparation Example 2, the pH only decreasedto 5.8.

Use Example C

[0053] Using 0.60 g of the product according to Preparation Example 8, afinal pH of 4.0 was reached. Using 0.71 g of the product according toPreparation Example 7, a final pH of 4.3 was reached.

Use Example D

[0054] Using 0.71 g of the product according to Preparation Example 10,a final pH of 4.3 was reached. Using 0.85 g of the product according toPreparation Example 9, a final pH of 4.7 was reached.

Use Example E

[0055] Using 0.82 g of the product according to Preparation Example 13,a final pH of 4.9 was reached. Using 0.94 g of the product according toPreparation Example 12, a final pH of 5.0 was reached. Using 1.27 g ofthe product according to Preparation Example 11, the pH only decreasedto 5.5.

1. Condensation product of a glycol, of a diglycol, of a higher glycolor of a glycerol with an α-hydroxycarboxylic acid in a molar ratio of1:2 or higher.
 2. Product according to claim 1, characterized in thatthe α-hydroxycarboxylic acid used has the general formula (I)

where r is hydrogen or a C₁₋₃ alkyl group, preferably hydrogen ormethyl.
 3. Product according to claim 1, characterized in that theglycol, diglycol or higher glycol used has the general formula (II)

where R′ is C₁₋₄ alkylene, preferably ethylene, and y is not less than1, preferably from 1 to 5, especially 1 or
 2. 4. Product according toclaim 1, characterized in that glycerol is used.